Displaying publications 121 - 136 of 136 in total

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  1. Caracelli I, Maganhi SH, Stefani HA, Gueogjian K, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Mar 01;71(Pt 3):o154-5.
    PMID: 25844223 DOI: 10.1107/S2056989015002157
    In the title compound, C15H8O2S, the coumarin moiety is approximately planar (r.m.s. deviation of the 11 non-H atoms = 0.025 Å) and is slightly inclined with respect to the plane of the thio-phen-3-yl ring, forming a dihedral angle of 11.75 (8)°. In the crystal, the three-dimensional architecture features a combination of coumarin-thio-phene C-H⋯π and π-π [inter-centroid distance = 3.6612 (12) Å] inter-actions.
  2. Rosely SN, Hussen RS, Lee SM, Halcovitch NR, Jotani MM, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2017 Mar 01;73(Pt 3):390-396.
    PMID: 28316817 DOI: 10.1107/S2056989017002365
    The title diorganotin compound, [Sn(CH3)2(C28H32N2O4)], features a distorted SnC2NO2 coordination geometry almost inter-mediate between ideal trigonal-bipyramidal and square-pyramidal. The dianionic Schiff base ligand coordinates in a tridentate fashion via two alkoxide O and hydrazinyl N atoms; an intra-molecular hy-droxy-O-H⋯N(hydrazin-yl) hydrogen bond is noted. The alk-oxy chain has an all-trans conformation, and to the first approximation, the mol-ecule has local mirror symmetry relating the two Sn-bound methyl groups. Supra-molecular layers sustained by imine-C-H⋯O(hy-droxy), π-π [between dec-yloxy-substituted benzene rings with an inter-centroid separation of 3.7724 (13) Å], C-H⋯π(arene) and C-H⋯π(chelate ring) inter-actions are formed in the crystal; layers stack along the c axis with no directional inter-actions between them. The presence of C-H⋯π(chelate ring) inter-actions in the crystal is clearly evident from an analysis of the calculated Hirshfeld surface.
  3. Yusof EN, Ravoof TB, Tahir MI, Jotani MM, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2017 Mar 01;73(Pt 3):397-402.
    PMID: 28316818 DOI: 10.1107/S2056989017002419
    The complete mol-ecule of the title hydrazine carbodi-thio-ate complex, [Ni(C19H21N2S2)2], is generated by the application of a centre of inversion. The NiII atom is N,S-chelated by two hydrazinecarbodi-thio-ate ligands, which provide a trans-N2S2 donor set that defines a distorted square-planar geometry. The conformation of the five-membered chelate ring is an envelope with the NiII atom being the flap atom. In the crystal, p-tolyl-C-H⋯π(benzene- i Pr), i Pr-C-H⋯π(p-tol-yl) and π-π inter-actions [between p-tolyl rings with inter-centroid distance = 3.8051 (12) Å] help to consolidate the three-dimensional architecture. The analysis of the Hirshfeld surface confirms the importance of H-atom contacts in establishing the packing.
  4. Yeo CI, Halim SN, Ng SW, Tan SL, Zukerman-Schpector J, Ferreira MA, et al.
    Chem Commun (Camb), 2014 Jun 7;50(45):5984-6.
    PMID: 24763907 DOI: 10.1039/c4cc02040e
    Evidence for C-H···π(CuCl···HNCS) interactions, i.e. C-H···π(quasi-chelate ring) where a six-membered quasi-chelate ring is closed by an N-H···Cl hydrogen bond, is presented based on crystal structure analyses of (Ph3P)2Cu[ROC(=S)N(H)Ph]Cl. Similar intramolecular interactions are identified in related literature structures. Calculations suggest that the energy of attraction provided by such interactions approximates 3.5 kcal mol(-1).
  5. Zukerman-Schpector J, Madureira LS, Wulf GD, Stefani HA, Vasconcelos SN, Ng SW, et al.
    Molecules, 2014;19(2):1990-2003.
    PMID: 24531216 DOI: 10.3390/molecules19021990
    Two independent molecules that differ in terms of rotation about the central S-N bond comprise the asymmetric unit of the title compound 1. The molecules have a V-shape with the dihedral angles between the fused ring system and benzene ring being 79.08(6)° and 72.83(5)°, respectively. The packing is mostly driven by p···p interactions occurring between the tolyl ring of one molecule and the C6 ring of the indole fused ring system of the other. DFT and IRC calculations for these and related 1-(arylsulfonyl)indole molecules showed that the rotational barrier about the S-N bond between conformers is within the 2.5-5.5 kcal/mol range. Crystal data for C16H13NO3S (1): Mr = 299.33, space group Pna21, a = 19.6152(4) Å, b = 11.2736(4) Å, c = 12.6334(3) Å, V = 2793.67(13) Å3, Z = 8, Z' = 2, R = 0.034.
  6. Mansoor MA, Ismail A, Yahya R, Arifin Z, Tiekink ER, Weng NS, et al.
    Inorg Chem, 2013 May 20;52(10):5624-6.
    PMID: 23627942 DOI: 10.1021/ic302772b
    Perovskite-structured lead titanate thin films have been grown on FTO-coated glass substrates from a single-source heterometallic molecular complex, [PbTi(μ2-O2CCF3)4(THF)3(μ3-O)]2 (1), which was isolated in quantitative yield from the reaction of tetraacetatolead(IV), tetrabutoxytitanium(IV), and trifluoroacetic acid from a tetrahydrofuran solution. Complex 1 has been characterized by physicochemical methods such as melting point, microanalysis, FTIR, (1)H and (19)F NMR, thermal analysis, and single-crystal X-ray diffraction (XRD) analysis. Thin films of lead titanate having spherical particles of various sizes have been grown from 1 by aerosol-assisted chemical vapor deposition at 550 °C. The thin films have been characterized by powder XRD, scanning electron microscopy, and energy-dispersive X-ray analysis. An optical band gap of 3.69 eV has been estimated by UV-visible spectrophotometry.
  7. Tan YS, Ooi KK, Ang KP, Akim AM, Cheah YK, Halim SN, et al.
    J Inorg Biochem, 2015 Sep;150:48-62.
    PMID: 26086852 DOI: 10.1016/j.jinorgbio.2015.06.009
    In the solid state each of three binuclear zinc dithiocarbamates bearing hydroxyethyl groups, {Zn[S2CN(R)CH2CH2OH]2}2 for R = iPr (1), CH2CH2OH (2), and Me (3), and an all alkyl species, [Zn(S2CNEt2)2]2 (4), features a centrosymmetric {ZnSCS}2 core with a step topology; both 1 and 3 were isolated as monohydrates. All compounds were broadly cytotoxic, specifically against human cancer cell lines compared with normal cells, with greater potency than cisplatin. Notably, some selectivity were indicated with 2 being the most potent against human ovarian carcinoma cells (cisA2780), and 4 being more cytotoxic toward multidrug resistant human breast carcinoma cells (MCF-7R), human colon adenocarcinoma cells (HT-29), and human lung adenocarcinoma epithelial cells (A549). Based on human apoptosis PCR-array analysis, caspase activities, DNA fragmentation, cell apoptotic assays, intracellular reactive oxygen species (ROS) measurements and human topoisomerase I inhibition, induction of apoptosis in HT-29 cells is demonstrated via both extrinsic and intrinsic pathways. Compounds 2-4 activate the p53 gene while 1 activates both p53 and p73. Cell cycle arrest at the S and G2/M phases correlates with inhibition of HT-29 cell growth. Cell invasion is also inhibited by 1-4 which is correlated with down-regulation of NF-κB.
  8. Ooi KK, Yeo CI, Ang KP, Akim AM, Cheah YK, Halim SN, et al.
    J Biol Inorg Chem, 2015 Jul;20(5):855-73.
    PMID: 26003312 DOI: 10.1007/s00775-015-1271-5
    The phosphanegold(I) carbonimidothioates, Ph3PAu{SC(OR)=NC6H4Me-4} for R = Me (1), Et (2) and iPr (3), feature linear P-Au-S coordination geometries and exhibit potent in vitro cytotoxicity against HT-29 colon cancer cells in both monolayer and multi-cellular spheroid models (e.g., IC50 = 11.9 ± 0.4 and 20.3 ± 0.3 μM for 2, respectively). Both intrinsic and extrinsic pathways of apoptosis are demonstrated by human apoptosis PCR array analysis, caspase activities, DNA fragmentation and cell apoptotic assays. Compounds 1-3 induce an extrinsic pathway that leads to down-regulation of NFκB. Compound 2 also exhibits an extrinsic apoptotic pathway involving the activation of both p53 and p73, whereas 3 activates p53 only. Lys48- and Lys63-linked polyubiquitination are also promoted by 1-3. Each of cytotoxic Ph3PAu{SC(OR)=NC6H4Me-4}, for R = Me (1), Et (2) and iPr (3), induce an intrinsic apoptotic pathway as well as an extrinsic pathway leading to down-regulation of NFκB. Lys48- and Lys63-linked polyubiquitination are promoted by 1-3 and these are able to inhibit cell invasion and to suppress the activity of TrxR.
  9. Cardoso LN, Nogueira TC, Wardell JL, Wardell SM, de Souza MV, Jotani MM, et al.
    Acta Crystallogr E Crystallogr Commun, 2016 Jul 01;72(Pt 7):1025-31.
    PMID: 27555956 DOI: 10.1107/S2056989016009968
    In the title carbohydrazide, C10H7N3O4S, the dihedral angle between the terminal five-membered rings is 27.4 (2)°, with these lying to the same side of the plane through the central CN2C(=O) atoms (r.m.s. deviation = 0.0403 Å), leading to a curved mol-ecule. The conformation about the C=N imine bond [1.281 (5) Å] is E, and the carbonyl O and amide H atoms are anti. In the crystal, N-H⋯O hydrogen bonds lead to supra-molecular chains, generated by a 41 screw-axis along the c direction. A three-dimensional architecture is consolidated by thienyl-C-H⋯O(nitro) and furanyl-C-H⋯O(nitro) inter-actions, as well as π-π inter-actions between the thienyl and furanyl rings [inter-centroid distance = 3.515 (2) Å]. These, and other, weak inter-molecular inter-actions, e.g. nitro-N-O⋯π(thien-yl), have been investigated by Hirshfeld surface analysis, which confirms the dominance of the conventional N-H⋯O hydrogen bonding to the overall mol-ecular packing.
  10. Md Yusof EN, S A Ravoof TB, Tiekink ER, Veerakumarasivam A, Crouse KA, Mohamed Tahir MI, et al.
    Int J Mol Sci, 2015 May 15;16(5):11034-54.
    PMID: 25988384 DOI: 10.3390/ijms160511034
    Two bidentate NS ligands were synthesized by the condensation reaction of S-2-methylbenzyldithiocarbazate (S2MBDTC) with 2-methoxybenzaldehyde (2MB) and 3-methoxybenzaldehyde (3MB). The ligands were reacted separately with acetates of Cu(II), Ni(II) and Zn(II) yielding 1:2 (metal:ligand) complexes. The metal complexes formed were expected to have a general formula of [M(NS)2] where M = Cu2+, Ni2+, and Zn2+. These compounds were characterized by elemental analysis, molar conductivity, magnetic susceptibility and various spectroscopic techniques. The magnetic susceptibility measurements and spectral results supported the predicted coordination geometry in which the Schiff bases behaved as bidentate NS donor ligands coordinating via the azomethine nitrogen and thiolate sulfur. The molecular structures of the isomeric S2M2MBH (1) and S2M3MBH (2) were established by X-ray crystallography to have very similar l-shaped structures. The Schiff bases and their metal complexes were evaluated for their biological activities against estrogen receptor-positive (MCF-7) and estrogen receptor-negative (MDA-MB-231) breast cancer cell lines. Only the Cu(II) complexes showed marked cytotoxicity against the cancer cell lines. Both Schiff bases and other metal complexes were found to be inactive. In concordance with the cytotoxicity studies, the DNA binding studies indicated that Cu(II) complexes have a strong DNA binding affinity.
  11. Jamaludin NS, Goh ZJ, Cheah YK, Ang KP, Sim JH, Khoo CH, et al.
    Eur J Med Chem, 2013 Sep;67:127-41.
    PMID: 23856069 DOI: 10.1016/j.ejmech.2013.06.038
    The synthesis and characterisation of R3PAu[S2CN((i)Pr)CH2CH2OH], for R = Ph (1), Cy (2) and Et (3)4, is reported. Compounds 1-3 are cytotoxic against the doxorubicin-resistant breast cancer cell line, MCF-7R, with 1 exhibiting greater potency and cytotoxicity than either of doxorubicin and cisplatin. Based on human apoptosis PCR-array analysis, caspase activities, DNA fragmentation, cell apoptotic assays, intracellular reactive oxygen species (ROS) measurements and human topoisomerase I inhibition, induction of apoptosis by 1, and necrosis by 2 and 3, are demonstrated, by both extrinsic and intrinsic pathways. Compound 1 activates the p53 gene, 2 activates only the p73 gene, whereas 3 activates both the p53 and p73 genes. Compounds 1 and 3 activate NF-κB, and each inhibits topoisomerase I.
  12. Low ML, Maigre L, Tahir MI, Tiekink ER, Dorlet P, Guillot R, et al.
    Eur J Med Chem, 2016 Sep 14;120:1-12.
    PMID: 27183379 DOI: 10.1016/j.ejmech.2016.04.027
    Copper (II) complexes synthesized from the products of condensation of S-methyl- and S-benzyldithiocarbazate with 2,5-hexanedione (SMHDH2 and SBHDH2 respectively) have been characterized using various physicochemical (elemental analysis, molar conductivity, magnetic susceptibility) and spectroscopic (infrared, electronic) methods. The structures of SMHDH2, its copper (II) complex, CuSMHD, and the related CuSBHD complex as well as a pyrrole byproduct, SBPY, have been determined by single crystal X-ray diffraction. In order to provide more insight into the behaviour of the complexes in solution, electron paramagnetic resonance (EPR) and electrochemical experiments were performed. Antibacterial activity and cytotoxicity were evaluated. The compounds, dissolved in 0.5% and 5% DMSO, showed a wide range of antibacterial activity against 10 strains of Gram-positive and Gram-negative bacteria. Investigations of the effects of efflux pumps and membrane penetration on antibacterial activity are reported herein. Antiproliferation activity was observed to be enhanced by complexation with copper. Preliminary screening showed Cu complexes are strongly active against human breast adenocarcinoma cancer cell lines MDA-MB-231 and MCF-7.
  13. Seng HL, Ong HK, Rahman RN, Yamin BM, Tiekink ER, Tan KW, et al.
    J Inorg Biochem, 2008 Nov;102(11):1997-2011.
    PMID: 18778856 DOI: 10.1016/j.jinorgbio.2008.07.015
    The binding selectivity of the M(phen)(edda) (M=Cu, Co, Ni, Zn; phen=1,10-phenanthroline, edda=ethylenediaminediacetic acid) complexes towards ds(CG)(6), ds(AT)(6) and ds(CGCGAATTCGCG) B-form oligonucleotide duplexes were studied by CD spectroscopy and molecular modeling. The binding mode is intercalation and there is selectivity towards AT-sequence and stacking preference for A/A parallel or diagonal adjacent base steps in their intercalation. The nucleolytic properties of these complexes were investigated and the factors affecting the extent of cleavage were determined to be: concentration of complex, the nature of metal(II) ion, type of buffer, pH of buffer, incubation time, incubation temperature, and the presence of hydrogen peroxide or ascorbic acid as exogenous reagents. The fluorescence property of these complexes and its origin were also investigated. The crystal structure of the Zn(phen)(edda) complex is reported in which the zinc atom displays a distorted trans-N(4)O(2) octahedral geometry; the crystal packing features double layers of complex molecules held together by extensive hydrogen bonding that inter-digitate with adjacent double layers via pi...pi interactions between 1,10-phenanthroline residues. The structure is compared with that of the recently described copper(II) analogue and, with the latter, included in molecular modeling.
  14. Chen BJ, Jamaludin NS, Khoo CH, See TH, Sim JH, Cheah YK, et al.
    J Inorg Biochem, 2016 10;163:68-80.
    PMID: 27529597 DOI: 10.1016/j.jinorgbio.2016.08.002
    Four compounds, R3PAu[S2CN(CH2CH2OH)2], R=Ph (1) and cyclohexyl (2), and Et3PAuS2CNRꞌ2, Rꞌ=Rꞌ=Et (3) and Rꞌ2=(CH2)4(4), have been evaluated for antibacterial activity against a panel of 24 Gram positive (8) and Gram negative (16) bacteria. Based on minimum inhibitory concentration (MIC) scores, compounds 1 and 2 were shown to be specifically potent against Gram positive bacteria whereas compounds 3 and, to a lesser extent, 4 exhibited broad range activity. All four compounds were active against methicillin resistant Staphylococcus aureus (MRSA). Time kill assays revealed the compounds to exhibit both time- and concentration-dependent pharmacokinetics against susceptible bacteria. Each compound was bactericidal against one or more bacteria with 3 being especially potent after 8h exposure; compounds 1 and 3 were bactericidal against MRSA. Compound 3 was the most effective bactericide across the series especially toward B. subtilis, S. saprophyticus, A. hydrophila, P. vulgaris, and V. parahaemolyticus. This study demonstrates the potential of this class of compounds as antibacterial agents, either broad range or against specific bacteria.
  15. Ishak DH, Ooi KK, Ang KP, Akim AM, Cheah YK, Nordin N, et al.
    J Inorg Biochem, 2014 Jan;130:38-51.
    PMID: 24176918 DOI: 10.1016/j.jinorgbio.2013.09.018
    The compound with R=CH2CH3 in Bi(S2CNR2)3 (1) is highly cytotoxic against a range of human carcinoma, whereas that with R=CH2CH2OH (2) is considerably less so. Both 1 and 2 induce apoptosis in HepG2 cells with some evidence for necrosis induced by 2. Based on DNA fragmentation, caspase activities and human apoptosis PCR-array analysis, both the extrinsic and intrinsic pathways of apoptosis have been shown to occur. While both compounds activate mitochondrial and FAS apoptotic pathways, compound 1 was also found to induce another death receptor-dependent pathway by induction of CD40, CD40L and TNF-R1 (p55). Further, 1 highly expressed DAPK1, a tumour suppressor, with concomitant down-regulation of XIAP and NF-κB. Cell cycle arrest at the S and G2/M phases correlates with the inhibition of the growth of HepG2 cells. The cell invasion rate of 2 is 10-fold higher than that of 1, a finding correlated with the down-regulation of survivin and XIAP expression by 1. Compounds 1 and 2 interact with DNA through different binding motifs with 1 interacting with AT- or TA-specific sites followed by inhibition of restriction enzyme digestion; 2 did not interfere with any of the studied restriction enzymes.
  16. Yeo CI, Ooi KK, Akim AM, Ang KP, Fairuz ZA, Halim SN, et al.
    J Inorg Biochem, 2013 Oct;127:24-38.
    PMID: 23850666 DOI: 10.1016/j.jinorgbio.2013.05.011
    The Ph3PAu[SC(OR)=NPh], R=Me (1), Et (2) and iPr (3), compounds are significantly cytotoxic to the HT-29 cancer cell line with 1 being the most active. Based on human apoptosis PCR-array analysis, caspase activities, DNA fragmentation, cell apoptotic assays, intracellular reactive oxygen species (ROS) measurements and human topoisomerase I inhibition, induction of apoptosis is demonstrated and both the extrinsic and intrinsic pathways of apoptosis have been shown to occur. Compound 1 activates the p73 gene, whereas each of 2 and 3 activates the p53 gene. An additional apoptotic mechanism is exhibited by 2, that is, via the JNK/MAP pathway.
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